Multirange measuring system



March 23, 1954 l. M. STEIN ET AL 2,673,136

MULTIRANGE MEASURING SYSTEM Filed Sept. 22, 1948 e Sheets-Sheet 1 I i 52 49 I 4 9 l I INVENTORS IRVING MA fiTE/N ALBERT .1. WILLIAMS JR. y FRANK F. DERN, JR.

A TTORNE Y5 March 23, 1954 M. STEIN ET AL MULTIRANGE MEASURING SYSTEM 6 Sheets-Sheet 2 Filed Sept. 22, 1948 lllllIllllilllllllllll III IIIIIII IIII' IIII ALBEFTJ. W/ZL/AMJLe/X BY A? an. Wfi

INVENTORS (IA/K r.- BERN,

A TTOfi/VFYS llllllll L |||||l||||||||| Illl lll March 23, 1954 1. M. STEIN ET AL MULTIRANGE MEASURING SYSTEM 6 Sheets-Sheet 5 Filed Sept. 22, 1948 ATTORNEYS March 23, 1954' I. M. STEIN ETAL 36 MULTIRANGE MEASURING SYSTEM Filed Sept. 22, 1948 6 Sheets-Sheet 4 I NVENTORS //?wNG M. srs/zv ALBERT .1, WILLIAMS,L//?. By FRANK E DERN, JR.

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ATTORNEYS March 23, 1954 1. M. STEIN ET AL 2,673,136

MULTIRANGE MEASURING SYSTEM Filed Sept. 22, 1948 6 Sheets-Sheet 5 Fly/k3 1914 //2 ma M 5? IN VEN TORS A TTORNEVS March 23, 1954 l. M. STEIN 'ET AL MULTIRANGE MEASURING SYSTEM 6 Sheets-Sheet 6 Filed Sept. 22, 1948 INVENTORS //?VM/G A4. STE/N AL BERT 0. M44 III/473% FRANK F. 051mm.

m ATTORNEYS Patented Mar. 23, 1954 2,673,136 MULTIRAN GE MEASURING SYSTEM Irving M. Stein and Albert J.

Williams, J1'., Philadelphia, and Frank F. Dern, Jr., Willow Grove, Pa., assignors to Leeds and Northrup Company, Philadelphia, Pa., a corporation of Pennsylvania Application September 22, 1948, Serial No. 50,638

14 Claims.

This invention relates to multi-range measuring systems, and particularly concerns self-balancing arrangements in which there is provision for indicating or recording a limit of the particular range in use in addition to indicating or recording magnitudes of the measured condition within the limits of that range.

Ge erally in accordance with the present invention, as the slidewire or equivalent circuit element of a self-balancing measuring network approaches either limit of its range of adjustment, it actuates a control switch in circuit with a motor device which, upon energization, effects a step of adjustment of a range-impedance and concurrently re-positions the range-indicating or rangerecording element. A second control switch deenergizes the motor allowing time for the rebalancing mechanism of the network to move the slidewire from its aforesaid limit if the adjustment of the range-impedance has been sufficient, and if not, to provide for one or more additional adjusting steps thereof as may be necessary.

In some forms of the invention, the aforesaid motor device is of the solenoid type energizable for selective actuation of directional ratchet mechanisms, and the aforesaid second control switch therefor is independently operated as by a thermostat or a motor-driven cam. In other forms of the invention, the motor device is a reversible motor whose armature is coupled to an actuator for the aforesaid second controlled switch, and in a preferred arrangement the armature is coupled to the range switch through a Geneva mechanism to efiect a step adjustment well before deenergization of the motor by the aforesaid second control switch. In another preferred arrangement, the motor is an alternating current motor which is plugged by direct current upon actuation of the aforesaid second control switch so as to prevent overrunning of the range switch contact.

In those forms of the invention providing for periodic printing of the selected range upon a recorder chart, an inking pad or roll is moved into and out of engagement with the rangeprinting element as the latter moves from its inactive position toward engagement with the recorder chart. In one embodiment involving printing, the printing mechanism is temporarily disabled during a range-stepping operation to preclude injury to the printing element or its inking element. More specifically, a small generator driven with the rebalancing slidewire produces during, a range-stepping operation, suflicient output to efiect movement of a lock bar or equivalent preventing operation of the printing mechanism during the range-stepping operation.

The invention further resides in features of construction, operation and arrangement hereinafter described and claimed.

For a more detailed understanding of the invention and for illustration of various embodiments thereof, reference is made to the accompanying drawings in which:

Fig. 1 schematically illustrates a multi-range measuring system embodying the invention;

Fig. 2 is a schematic circuit diagram of a ratchet motor device and control circuit utilizable in the system of Fig. 1;

Figs. 3 and 4 are detail views of one form of ratchet type of motor device utilizable in the control circuits of Figs. 2 and '7;

Figs. 5 and 6 are views of another form of ratchet motor device utilizable in the circuits of Figs. 2 and 7;

Fig. 7 is similar to Fig. 2 differing in the type of intermittent control switch;

Figs. 8, 9 and 10 illustrate further modifications of range-stepping motors and control circuits each utilizable in the system of Fig. 1;

Figs. 11 and 12 illustrate composite range and Vernier indicators utilizable in the system of Fig. 1;

Figs. 13 and 14 are views of printing mechanism utilizable in the systems of Figs. 1, 16 and 17;

Fig. 15 illustrates another form of printing mechanism utilizable in the systems of Figs. 1 and 17;

Fig. 16 schematically illustrates a measuring system using measuring and range networks with a common unbalance detector;

Fig. 17 schematically illustrates a multi-range measuring system using a multi-turn slidewire provided, inter alia, with a tractor printing element repeatedly covering a scale corresponding with a fraction of the total range of the slidewire;

Fig. 18 is a detail view on enlarged scale of the tractor chain used in Fig. 17;

Fig. 19 illustrates an arrangement for disabling the recorder-printing mechanism during rangestepping adjustment;

Figs. 20-22 illustrate one form of printing mechanism, the successive figures showing the successive positions of the printing and inking members;

Fig. 23 schematically illustrates a measuring system having two or more range impedances; and

Fig. 24 is a perspective view of an arrangement work controls a reversible .afiorded by slidewire 14 .lower limit of its range of adjustment.

suited for effecting printing and inking movements of recorder mechanism shown in Fig. 23.

Referring to Fig. 1, the block 10 is generically representative of a measuring network such as a potentiometer, bridge or the like which is unbalanced in response to the change in magnitud of a condition, such as temperature, pressure, ionconcentration or other variable to which an appropriate primary device H is responsive. By way of example, the primary device may be a thermocouple, a resistance-thermometer, a pH cell, or other device for producing an electrical effect varying as a function of the condition to be measured. A suitable detector 12 responsive to th unbalance of the network In controls a rebalancing mechanism or device generically represented by the block 13 to eiiect adjustment of the slidewire 14 of the network l in proper sense to restore it to balance. The detector 12 may be a galvanometer as in Squibb Patent No.

1,935,732 andthe rebalancing mechanism l3 may be of th mechanical type shown in that patent:

or the detector and the rebalancing mechanism may be of the types shown in Williams Patents Nos. 2,113,164 and 2,113,436 in which a thermionic amplifier in response to unbalance of the netmotor to effect a high speed rebalancing adjustment of slidewire l4. InFig. 1 and subsequent figures, the electrical or mechanical connection between detector 12 and rebalancing mechanism 13 is generically represented. by line 24.

The slidewire I4 is coupled as by a flexible cord 11 to an exhibiting element 15 movable with respect to a stationary scale 18; alternatively, or in addition, the exhibiting element i may be a recorder stylus or pen, producing a continuous or intermittent trace on a recorder chart 25 hav- .ing a scale 16A of extent corresponding with the rangeof slidewire movement. The driving cord 11 for pen or stylus I5 is driven by pulley 30 suitably coupled to shaft 21. The chart r011 29 is driven at low constant speed by an electric motor 26. or equivalent.

The measuring network l0 includes a rangechanging impedance i8 adjustable step-by-step to extend the range of measurement beyond that itself. By way of example, each section of the impedance 18 may correspond with a substantial fraction of the rangeof slidewire 14 thu to provide consecutive ranges. of measurement preferably with slight overlap. The stepping adjustments of impedance l8 are effected by a motor device, generically represented in Fig. 1 by block 19, which is energized automatically to effect a step adjustment of the impedance 18 in one sense or the other when theslidewire I4 is moved to the upper or Several specifically difierent forms or motor device 19 are herein later described. In each of their control systems, a control member 2611 is engaged by acam or arm 21 on the shaft 21 when the slidewire 14 reaches approximately the low limit of its range of adjustment to effect energization 'ormotor device 13 for adjustment of impedance 18 to the next lower measuring range. When the slidewire 1:4 is adjusted to the high limit of its range of adjustment, the control arm 21 engages the other motor control member 203 for energization of the motor device I3 in proper sense, to advance the impedance 18 to the next higher range.

Concurrently with each stepping adjustment of impedance 18, a second exhibiting element 22 V tacts 20A, 20B, the impedance I8 is moved with respect to a stationary range-indicating scale 23; alternatively, or in addition, the exhibiting element 22 may serve as a stylus or pen to cooperate with a range-scale 23A of the recorder chart 25.

By way of example, assuming the device is for measurement of temperatures from 0 to the range of adjustment of slidewire l4 may correspond with an eleven-degree change and the total range of adjustment of impedance 18 may correspond with ten 10 changes. Accordingly, the pointer or pen .22 gives a coarse indication or record of the temperature and the position of pen or pointer 15 gives the fine or Vernier indication on the extended scale 16 or 16A and, in the specific example assumed, the positions, in Fig. 1, of the two pens or pointers correspond with a temperature of 65, the position of pointer 22 corresponding with the range digit 6 and the position of pointer 15 corresponding with the slidewire digit 5,

In the particular form of range-changing mechanism 19 and control system therefor shown in Fig. 2, the control members 20A and 20B are movable switch contacts moved into engagement with fixed contact 31 by control arm or cam 21 as the slidewire l4 arrives at or about one or the other limits of its travel thus to select for energization one or the other of the solenoids 32, 33. Assuming the coil solenoid 32 is energized, .its core or armature 34 is moved downwardly to effect a one-step adjustment of the contact 43 of impedance I8 in counterclockwise direction through the pawl 36 and ratchet, 31. Conversely, if the solenoid 33 is energized, the movement of its core 35 is transmitted through the pawl 38 and ratchet 39 to effect a one-stepclockwise adjustment of the range-contact 49.

As thus far described, in event of a sudden change in the magnitude of the, measured condition to extent corresponding with more than one stepping adjustment of impedance 18,. the solenoid 32 or 33 would remain energized at the end of one stepping adjustment and accordingly the range of measurement would not be sufilciently increased or decreased. In the particular arrangement shown in Fig. 2, this difficulty is overcome by inclusion in the energizing circuit of the solenoids of a switch 42 periodically actuated by cam 41 driven by motor 40 for convenience supplied from the same A. C. or D. C. power line 43, 43 provided for energization of the solenoids. Therefore, so long as the slidewire-limit cam 2| maintains engagement between contact 31 and one or the other of the motor control conis intermittently advanced step-by-step until there is a reverse-adjustment of the slidewlre 14 which occurs when the balance point of the measuringnetwork H) has been brought within the limits of one; of the measuring ranges afforded by impedance 18 The interval between successive closures of switch 42 is sufiiciently long to allow the detector l2and rebalancing mechanism 13 to determin whether the range has been shifted to suitable extent and if so, to move the slidewire 14 away from its upper or lower limit as the case may be.

In the particular form of range-stepping mechanism 19A shown in Figs. 3 and 4, the ratchets 39 and 31 ar rotatably mounted upon a. shaft 44 and upon their-hubs is rotatably mounted a differential drum 45. The rings 41, 48 which threadably engage the opposite ends of thedrum are tightened to clamp the contacts 49 of rangeimpedance l8 andthe interleavedspacing rings 46. Asithe drum 45 rotated in manner :la-ter 5 described, the range contacts 49 successively engage fixed contacts (not shown) of a drum-switch to effect step-by-step adjustment of the rangeimpedance.

The bevel bears 5t and 5| of the differential, respectively fastened to the ratchets 38 and 31 for rotation therewith, engage the idler gear 52 and 53 which are freely rotatable on the stub shafts 54, 54 extending inwardly from the drum or barrel d5 of the differential. Actuation of ratchet 31 by solenoid 32 effects angular movement of the contact barrel 45 in counterclockwise direction and through an angle which is one-half that of the movement of ratchet 31; similarly, actuation of ratchet 39 by its solenoid 33 effects movement of the contact drum in clockshown in Fig. 3, the actuating pawl 36 of ratchet 31 is pivoted upon an arm 55 rotatable upon shaft 44 and connected by link. 58 to core 34: similarly, the actuating pawl 38 f ratchet 39 is pivoted upon an arm 55 rotatable upon shaft 44 and connected by a link 59 to core 35.

Thus, as will be understood from the prior description of Figs. 1 and 2, when the slidewire M has been adjusted to one limit of its movement, one of the ratchets 33, 31 is actuated to shift the range contacts 49 in corresponding sense and'conversely, when the slidewire US has been adjusted to the other limit of its movement, the other of the ratchets is actuated to adjust the impedance [8 in reverse sense. If the slidewire remains at either limit of its travel, the corresponding ratchet is actuated as many times as is necessary to shift the measuring range so that balance of network 3 may be effected by adjustment of slidewire [4: the initial step is effected by the last closing of switch 42 and contact 20A (or 211B) and all subsequent steps, if any, are effected by reclosure of switch 42.

Another form of range-adjusting device 19B is shown in Figs. and 6. It is generally similar to that shown in Figs. 3 and 4 and accordingly, corresponding elements of both forms have been identified by like reference characters. In this modification, the ratchets 31 to the shaft 69 of a wafer-type switch whose contacts provide for adjustment of the rangeimpedance it, generally as described in connection with Fig. 1. The pawl-supporting arms iii and 62, freely pivotally mounted upon shaft 69, are biased by spring mean the fixed stops B5, 38.

the pawl member 66 is pivotally mounted upon arm 62 and is connected by link 61 to the core 35 of solenoid 33. As will be understood from the prior description of Fig. 2, when one or the other of solenoids 32, 33 is energized, the associated pawl and ratchet effects stepping adjustment in proper sense of the movable contact structure of the range-impedance I 8.

Preferably, there may be attached to the shaft 69, a disk 12 whose periphery is notched to engage the ball or detent ll of a spring-latch arrangement, the position of notche in the detent wheel 12 corresponding with the contact positions.

Either of the ratchet stepping mechanisms ISA, I 93 may be used in the motor-control system of Fig. 2 Or of Fig. 7. In th latter, the periodically operated switch 42 of Fig. 2 is replaced by a thermostatically operated switch 1? preferably provided with a magnetic snap exemplified by magnet 18. When the cam 2| on the slidewire and 39 are secured shaft 21 is out of engagement with both of the control contacts 20A, 203, the heatercoil 16 is deenergized and the thermostat switch 11 is closed and remains so for an appreciable time after the cam 72! engages one or the other of contacts 26A, 263 to energize the corresponding stepor 33 and the heater 16. With at either limit of its range, the corresponding contact 23A or 2013 is held in engagement with contact 3! until one or more stepping adjustments of the ratchet mechanism so shift the measuring range that a reverse adjustment of the slidewire I4 is effected: the first step is effected by initial closure of contact 20A or 2113 and any subsequent steps are effected by reclosure of the thermostat switch 11.

A third form I 90 is shown in Fig. 8. To the shaft 92 of a small reversible motor 82 is attached a notched disk 86 for actuating a pair of movabl contacts 87A, 813. For energization' from alternatingcurrent, the motor 82 may be, as shown, a capacitor motor; a split-field series motor may be sued for operation on either alternating-current or direct-current. The motor shaft 92 is also connected through a slip-clutch or friction drive 30 to a movable contact 83 adapted to engage one or the other of the fixed contacts A, 853 in dependence upon the direction of rotation of the motor. When the slidewire I4 reaches one or the other of its limit of travel, the corresponding contact ZilA or 23B is moved into engagement with contact 3| so to initiate energization of the motor for adjustment of impedance I 8 in proper direction. As soon as the motor 82 begins to turn, a lock-in circuit i completed either through the contacts 83, 85B, 81B, 88B or through contacts 83, 35A, 81A, 38A depending upon the direction of rotation of the motor. It is thus insured that contact 49 of the rangeimpedance is will continue to move from one fixed contact to the next ven though the motor circuit through contact 23A or 29B is broken before the stepping adjustment is completed. At the end of a stepping adjustment, assuming contact 3! is not engaged by either of the starting contacts 23A, 2313, the motor circuit is deenergized under control of the notched disk 83 which effects separation of contacts 31A and 873 from the stationary contacts 83A, 383. If the starting switch 26A or 233 remains closed after completion of one stepping adjustment, the motor 82 will continue to run for one or more additional control cycles and so effect intermittent stepping of the range switch until the rebalancing mechanism IS in its adjustment of slidewire 14 moves the cam 2! away from the previously closed starting-switch 23A or 203.

By way of example, the motor shaft 92 may make one revolution per minute so that for a 12-point range switch, the disk 36 will have 12 notches and the motor 82 will run five seconds to move the disk 86 one notch.

The cams 39A and 89B are so driven through reduction gearing 33, 35 that limit-switch BIA is opened when the impedance I B is adjusted to one of its limits and that motor-limit switch BIB is opened when impedance I8 is adjusted to the other of its limits.

A modification I9D which provides more time than modification [90 between movement of the range switch and the end of the motor operation cycle, so to afford more time in which therecorder may come to balance, is shown in Fig. 9.

On the motor of range-stepping mechanism shaft 92 are fastened a multi-- lobed' camfil and a mutilated gear 93 having a correspondingnumber of equally spaced teeth. The shaft 92- also drives a movable contact 83 through a friction clutch 80. Also, as in the system'of Fig. 8, operation of the motor 82 is initiated upon engagement of cam 2I or equivalent with one-or the other of the control contacts=20A, 20B. Immediately after such a starting impulse, the motor circuit is completed through a lock-in circuit completed by closure of contact 83*with one or the other of contacts 85A, 85B and by the closure of contacts 81A, 08A or 81B, 883 under control of the four-lobed cam 9I. The motor continues to run until its circuit is interrupted under control of cam 9I which effects separation of contacts 81A, 81B from contacts 88A, 8813 respectively. Well before-the endof the cycle of motor energization, the mutilated gear 93 moves the associated gear through an arc corresponding with one step of adjustment of impedance I8, to afford sufficient time for the operation of the recorder to move cam2l away from contact 20A or 20B if within that cycle the measuring range has been shifted sufficiently to bring. the balance point of network Iwithin the new measuring range. If the extent of adjustment of impedance I8 has not been suflicient, the cam 2I remains against the corresponding starting contact 20A or 2013' and themotor cycle is immediately re-initiated, the

cycles continuing in uninterrupted sequence until cam'2I opens the starting contact 20Aor 203. In each cycle, the stepping adjustment of impedance I8 is followed by an interval sumciently long to permit the detector i2 and rebalancing deviceto act.

In the particular device I913, the shaft 92 rotates at a speed of one revolution per minute and the gear 93 has four teeth spaced 90 apart, so providing a motor period or cycle of fifteen seconds of which seven seconds are available for rebalancing of network I0 before the next cycle can be initiated. The gear reduction 00, 95 between the motor limit switches 89A, 89B and motor shaft 92 is such that when the impedance IBis adjusted to either limit of its travel, the motor cannot be energized for further movement in thesame direction but may of course be energized to effect a reverse adjustment of the impedance I8.

In Fig; there is shown a modification ISE of the systems of Figs. 8 and 9 which provides for braking. of the stepping motor 82 of the range-changing impedance. As shown, motor 82"is asplit-phase reversible induction motor.

When the motor 82 is at rest, rectified direct current flows through it in a circuit including the current-limiting resistor I42, the rectifier MI, contacts 81, 88B of the range-changing device, contacts I31, A, I33 and 20B of the motorstarting switch and contacts 03, 0513 (or 83, 85A) of-thefriction drive switch. When the slide wire I4 reaches either limit of its travel, the cam 2| engages either of the starting contacts 20A, 2013 to interrupt the direct-current circuit through the motor and to complete an A. C. circuit for starting of the motor through a corresponding one of contacts I38, I40. As soon as the motor starts, the friction-driven contact 83. moves to make the proper connection to keep the range-changing motor 02 operating in the direction it was started even though the starting, contactZD-A (or 203) return to the position shown in Fig. 10. Also, as. soon as the motorstarts. thernotched-disk 86A of the rangeswitch effects separation of contacts 81and 88B" to insure that the D. C. circuit isnot restored even though contacts 20A, 203'. return tothe position shown in Fig. 10. Thus, the rangechanging motor continues to operate on alternating-current to adjust contact 49 of the range impedance. Whilethe motor 82 is running, the rectifier MI charges the capacitor I43 so that when, at the end of a range step, the contact 01 is moved away from engagement with contact A and into engagement with contact 8815, the A. C. excitation of the motor is terminated and immediately thereafter the D. C. charge of condenser I43 is discharged through the motor to bring it to an abrupt stop.

As shown in Fig. 11, the range-scale with which the pointer 22 coasts and the Vernier scale with which the pointer I5 coacts may be combined in a single structure 96 instead of being separate as in Fig. 1. Alternatively, as shown in Fig. 12, the range disposed behind the Vernier scale I6 which in this case is provided with a window 93 through which the successive graduations or numerals of the range scale are successively visible as impedance I8 is adjusted to successive settings. Either of these arrangements may be used in substitution for the indicating shown in Fig. 1.

Figs. 13 i4 isclose an arrangement for printing a range limit in use upon the recorder chart instead of making a range trace as in Fig. l. The print wheel it?! having the various rangelimit designations thereon at circumferentially spaced intervals is supported by a bracket II2 mounted upon and movable with a rock-shaft I02. At fixed intervals, the shaft I02 is swung towards the recorder chart 25 to print thereon a number or other symbol indicating the rangeswitch setting in use. The bracket II2 carries a diiierential assembly comprising the drum I04 having internal stub upon which are freely rotatable the idler gears I06, Hi6. This drum is rotated in correspondence with the positions of the range switch by a flexible cord. I05, or

equivalent, so that printing wheel I03 is moved to positions corresponding with the setting of the range impedance.

The periphery of the printing wheel I03 is continuously in engagement with an inking wheel III and to provide that all characters on the wheel I03 be in readiness for printing, it is rotated between successive printing operations. To that end, the differential gear I00 is fastened to the shaft of a gear 500 which is intermittently.

coupled to the continuously rotating shaft I01 through a mutilated gear I08. The number of teeth of the mutilated driving gear I08 corresponds with the number of teeth of the driven gear I99 so that for eachrevolution of shaft I01, the print wheel m3 is rotated one revolution, the

time interval afforded by mutilation of gear I00 corresponding with the interval during which shaft I02 is rocked to effect a printing operation. As the wheel 103 rotates a complete revolution for each inking operation, it is returned each time to the setting corresponding with that or the range switch in readiness for the next printing operation. The drive of the print wheel I03 for inking is from gear I00 through the idler gears I06 to the gear IIO attached to the print wheel shaft. The rotation of the print wheel I03 forits inking does not affect the position of the drum' I05 which at all times corresponds with the existing setting or the range-changing switch.-

scale may be on a movable slide scale arrangement closed in Ross et al. Patent through the crank Another arrangement for printing the range setting on the recorder chart is shown in Fig. 1 The printing stylus 22 is carried by a rack member II 1 carried by a supporting bracket (not shown) equivalent to bracket I I2 of Fig. 13 which is attached to the rock shaft I02 of the recorder. The movable contact 49 of the impedance I 8 is coupled by gearing II flexible shaft H5 and gearing II4 to the rack-gear I It also supported by the supporting bracket of rackII'l. As the range-changing switch is stepped to its various settings, generally as described in connection with Fig. 1, the printing stylus 22 is concurrently moved to corresponding positions above the recorder chart. Accordingly, rack member I I7 is moved toward and away from the recorder chart in each cycle of the recorder, the stylus 22 makes a dot or impression on the range scale of the chart 25 to indicate the then existing range setting of impedance I 8.

Referring to Fig. 16, the measuring network IDA, shown by way of example, is a Wheatstone bridge of the type shown in Leeds Patent No. 1,097,651 for measurement of resistance, specifically the resistance of a temperature-responsive resistor II 8. With the contacts H9, I in the position shown in Fig. 16, the detector I2 is responsive to unbalance of the measuring network IIJA to effect a, rebalancing adjustment of the slidewires I 4A and I 4B of that network by the rebalancing mechanism I 3. Concurrently with adjustment of these slidewires, the recorder pen I5 is adjusted to corresponding position across the recorder chart above its Vernier scale 56A. Assuming the temperature change is so great as to be above or below the range afforded by the slidewires, the cam 2| on the slidewire shaft is effective, as in systems previously described, to actuate one or the other of control members 20A, 20B whereupon the motor device I9 effects a stepping adjustment of the range-changing resistor I 8A. Concurrently, with adjustment of resistor I 8A, there is effected a corresponding stepping adjustment of range-repeater resistor IBB in a second network I BE.

During continued operation of the recorder, the other constant speed device, is eifective through cam I to move the detector contacts H9, I 20 out of engagement with contacts I2I, I22 and into engagement with contacts I23, I24 thus to connect the detector I2 to the range-repeater network IBR. The rebalancing for recording on the coarse and fine scales may be canal or different: by way of example, the cam I25 may be so shaped and rotate at such speed that network IilA is connected to the detector for 2-second intervals and net work IIlR is connected to the detector for alternate 2-second intervals.

The mechanism for effecting the printing movements of the shaft I02 may be similar to that dis- No. 2,113,748. Generally as schematically shown in Fig. 16, the motor 25 drives a notched disk or cam I3I through gearing I32, I33. When the same notch is in alignment with a projection of lever I34, the latter is free to move under its biasing sprin I to actuate the link I and so rock the shaft I02 lever I36 to bring the pen I5 as the support for 10 into engagement with chart 25. Shortly thereafter the cam I3I returns the parts to the posi-- tion shown in Fig. 16.

As will be understood from the foregoing description of Fig. 16, one and the same pen I5, or equivalent, is used to print the coarse or range indications on scale 23A of chart 25 and the fine indications on scale I 6A of the chart. Alternatively, the scales IEA and 23A may be coextensive and the printing mechanism associated with pen i 5 so controlled, as in Fig. 4 of the aforesaid Ross Patent 2,113,748 as to make difierent traces, such as dots and dashes, respectively identifying the coarse and fine readings: or with coextensive scales ItA and 23A, the pen I5 may be replaced by a print Wheel, such as in Fig. 3 of the aforesaid Ross patent, having different printing elements to distinguish between the coarse and fine readings.

In Fig. 17 there is disclosed a recorder suited for accurate measurement of small changes of resistance or other variable over a substantial range. The multi-turn slidewire I iC is provided with a movable contact I 41 mechanically connected to the shaft of the rebalancing mechanism I3 by gears I50 and I 5| having such ratio that, for example, one revolution of the shaft 27 corresponds with a one-quarter turn of the slidewire MC. The ends of the slidewire I lC are connected to the measuring network Ill. The slidable contact I i? of slidewire MC is connected to one input terminal of detector I 2 through conductor I 45 which is wound around drum Hit parallel to the resistance wire forming the slidewire.

The rebalancing shaft 27 is also connected by flexible shaft i it to a tractor printing device I54, and more particularly to one of a pair of sprockets 257 of the device which hold taut an endless chain I55 from which extend three printing points 22B equally spaced along the chain at distances each equal to the circumference of the sprocket I52. Hence, for a one-quarter turn of the slidewire IiC, the chain I55 will move a distance equal to the length of scale I513 of the recorder chart. For the complete range of a 15- turn slidewire I 40, the shaft 21 will therefore make sixty revolutions rotating the sprocket I57 a like number of revolutions and causing sixty traverses of the chart by the printing points. The reduction gearing I48, I49 between the main shaft 21 and the driving pulley Elli for the pen I5 is so proportioned as to cause the pen to traverse the scale ItA once for the complete range of slidewire MC. In a particular instance, the scale IBA includes 60 chart divisions, each division corresponding with one-quarter turn of the slidewire MC and with the chart range i615 allocated to the printing-points 2213. The record made by the printing points 2213 for adjustment of slidewire IdC from one limit to the other is a series of sloped lines each corresponding with a quarter turn of the slidewire MC, while the concurrent record made by pen I5 is a continuous slope corresponding with the entire range of movement of the slidewire MC.

A hereinafter more fully described, the chain I55 and the printing points 22B are carried by a periodically rocked carriage supported from shaft I92 so that the sloped lines produced by them consist of a series of dots. The mechanism for effecting intermittent rocking of shaft I02 may be similar to that shown in the aforesaid Ross et al. patent and briefly described in connection with Fig. 15. The chain We consists of a series of U-shaped links I56, Fig. .18, to certain shaft of slidewire contact 2I of the range-stepping mechanism is such that l54 of Fig. 1'1 during the slidewire contact the rack bar H1 and printing point 22 is similar to that discussed in connection with Figl i and need not be further described.

It-shall be understood that the gear reduction afforded by gears I52, I53 between the actuator I41 and the control cam the control cam 2I respectively engages the control. members 20A and 2013 when the slidewire reaches the corresponding limits of its range of adjustment, specifically, for fifteen turns of the slidewire drum I44, the cam 2I actuates one or the other of control members 20A, 2013 to step the impedance I8 to the next higher or the next lower range as required.

The circuit and mechanism shown in Fig. 19 is to prevent damage to the tractor-printing device actuation of the range- Upon'a change in range, I41 (Fig. 1'1) is rapidly moved from one end of the slidewire towards the other so causing the points 22B on chain I55 to sweep across the printing zone of its travel at high speed. Since the inking and printing operations occur at frequent intervals, there is strong changing mechanism.

probability that inrange-changing the rapidly moving points 2213 may be brought into contact with the ink pad or chart with consequent injury.

Reverting to Fig. 19, the small generator or magneto-tachometer I68 is geared to the rebalancing motor 82, or equivalent, so that when the speed of the balancing motor is high, as during a range change, the output of the tachometer is sufficiently great to effect energization of a sensitive relay I12. The closure of the contacts I13, I14 of the relay effects energization of the solenoid I15. The resultant movement of the core I16 of the solenoid is transmitted to a lock-out bar I11 through a bell crank lever I18. The positioning of bar I11 in the path of the link I34 of the printing mechanism prevents the biasing spring I30 from effecting rocking movement of the shaft I02 of the recorder. There is thus prevented engagement of the printing points 22 and 22B'either with the inking pad or with the recorder chart. This will become more clear from the following description of the actual construction of a mechanism for bringing the printing points 22 and 22B first into contact with an inking pad (not shown in Fig. 17) and then into contact with the recorder chart.

The magneto I66, or equivalent, may also be used to inject into the measuring network I a voltage proportional to the speed of rebalance of the network in avoidance of overshooting of the balance point. The network comprising resistors I81, I89, I1I, varistor I and condenser I88 is included for the purpose of damping when the detector I2 is of the galvanometer type.

Referring to Figs. 20 to 22, the supporting sprockets I51 for the tractor chain or endless belt I55 are rotatably mounted upon a frame II2A which is secured to the rock shaft I02. To effect a printing operation, the shaft I02 is rocked, by mechanism previously described, from the position shown in Fig. 20 to the position shown in Fig. 22. During this movement, by mechanism nowdescribed, an inking pad I82 is brought into the path of the printing points 223 for transfer of ink thereto and then retracted to permit engagement of the" freshly inked'point or :points' with the '25 when the supporting chart. The. inking stripor .pad I82 is carried by a pair of arms I83 atopposite ends of the frame II2A. As only one end of the frame is shown, the description will be confined thereto, it being understood that a similar arrangement exists at the other end. The end of arm I83. remote from the inking pad I82 is pivotally connected at I94 to the free end of a lever I84 mounted at its other end upon the pivot I85 attached to the frame I HA. The link I84 is provided with a slot I86 which receives a stationary pin I81 secured to the frame of the recorder mechanism. The inking arm I83 is :biased by spring I88 into engagement with a stop I89, preferably a roller at the lower end of a slide I which is adjustably secured as byscrew I9I to the frame member II2A. With the parts in the inactive position shown in Fig. 20, the inking pad I82 is out of the path of the printing points 22B and the latter are away from thechart roll 29.

As the frame or mount I I2a is swung clockwise from the position shown in Fig. 20 to the'position shown in Fig. 21, the engagement of fixed pin I81 withthe slot or groove I86 causes the inking bar I83 to move to the left and when the inking pad I82 is in position below the path of the printing points 22B, the stop I89 moves into the notch I92 of the bar I83 allowing bar I83 to swing upwardly to the position shown in Fig. 21 for engagement of pad I82 by thetips of the printing points 223. As frame II2a continues to swing, now in counterclockwise direction, toward the position shown in Fig. 22, the engagement between the stationary pin I81 and the slot I86 of link I84 causes the arm I83 to move 'to the right away from the printingpoints to allow contact thereof with the recorder chart and the roller I89 comes into engagement with the sloping face I33 of the pad arm I83 to allow arm I83 to move, under the action of spring I88, toward the frame I In and away from the chart roll 29.

The inking arrangement described insures that the points 22B shall not be dry when moving into engagement with the chart 25.

In the arrangement shown in Figs. 23 and 24, when the contact of range-impedance I8 moves in one direction beyond the first fixed contact or beyond the lastfixed contact when moving in the opposite direction, the Geneva mechanism I91 is effective to adjust the movable contact of a second range-resistance I8D one step, backward or forward, depending upon the direction of movement of the contact of the first rangeimpedance ance I8 may be adjustable in nine steps of one ohm each and the range resistor I8D may be adjustable in nine steps each of ten ohms: thus, the total range of the two impedances is 99 ohms adjustable in one ohm steps from zero to 99, the slidewire giving a one ohm Vernier adjustment. The total measuring changed, the print wheel is moved to a corre-- sponding position so that the appropriatecharacter or numeral is impressed upon the chart bracket M213 is; rocked towards" the chart. Concurrently withoperation I8. 'By way of example, the impedrange may ob- A viously be extended by using another range reof the Geneva I9! to effect stepping adjustment of the second range impedance [8D, the Geneva mechanism 26! is efiective to step the second print Wheel [0313 one step forward or backward as the case may be. The second print wheel N313 and gear 202 of the Geneva mechanism rotate in unison upon the drive shaft 2833 of the print wheel 103A. The Geneva gear 23 rotates in unison with the print wheel (63A, and for each revolution thereof engages the bridging gear 2M which is suitably supported from the bracket 23. Although for clarity in Fig. 23 the printing wheels and Geneva elements are widely separated, actually the mechanism is quite compact so that the two print wheels 103B, iiltA are side by side, Fig. 24, so that the characters printed by wheel 13A appear in the digit column, and the characters printed by wheel [03B appear in the tens column.

The arrangement for effecting rocking movement of the frame HZB and for eiifecting inking of the print wheels 103A, [033 is shown in Fig. 24. The supporting bracket or frame H23 is biased for rotation about a stationary shaft 502A for movement toward the chart roll. The movements of the bracket HZB tovard and from the chart roll are controlled by the cams 2&5, 206. The former is attached to the shaft 251 which in a particular instrument rotates at a speed of about 25 revolutions per minute. The cam 206 is attached to a sleeve Elli? freely rotatable on shaft 20?, the sleeve being rotated at a much slower speed, for example, one revolution per minute through a gear train including the gears 209-2M. The bar or shaft 285 extending from the bracket H213 rides along the periphery of the cam 2G5 shaped generally as indicated in Fig. 24. The movement of the bracket I I2B towards the chart roll cannot occur until there exists a precise angular relationship between the two cams 2&5 and 2855. As shown in Fig. 24, to the end of shaft 255 is attached a roller 2|! which engages the periphery of cam 205. When the cams 295, 206 are of such angular position that cam follower MS may enter the notch 215 of cam 211% and roller or cam follower 2| 1 may enter the notch 258 of cam 205, then and then only are the print wheels brought into engagement with the chart paper. The print wheel support 2B is moved away from the chart roll by engagement between the rise of the more rapidly moving cam 2G5 and the cam follower 2 i 1 supported from bracket i 523.

In each printing cycle, the inking roller MBA is swung into and out of contact with the periphery of the print wheels IiliiA, W33 before they are brought into engagement with the chart 25. It is thus insured that the printing characters are inked even though the print wheels may long remain in the same range-position. The necessarily precise timing required for such movement of the inking roll is effected by cams Mil-21! which are fastened together with gear 752i upon a sleeve 222 freely rotatable upon the stud shaft [02A upon which bracket I IZB is pivotally mounted. The cams M9 and 220 are rotated in unison with the low speed cam 206 through the sleeve 208, gear 223 and aforesaid gear 22!. The cam followers 224 and 225 which respectively engage the cams 220 and 2 I 9 are supported from a crosshead 226 pivotally connected at 227 to crank arm 228 attached to one end of shaft 225. The arms 1,} 230, 230 for supporting the inking roll ESZA are attached to the other end of shaft 229. v Thus, between successive movements of the h range-impedance to its 14 printing wheels towards the recorder sheet, the inking roller H82 is swung into wiping engagement with the under faces of the printing wheels and is thereafter retracted.

It shall be understood the invention is not limited to the particular embodiments illustrated and described and that modifications may be made within the scope of the appended claims.

What is claimed is:

l. A recorder comprising a slidewire adjust able to balance a measuring network, a, printing element moved concurrently with adjustment of said slidewire, mechanism for periodically moving said element into engagement with the chart of said recorder, means producing an electrical eiifect of magnitude dependent upon the speed of adjustment of said slidewire, and electromechanical means responsive to said electrical eifect temporarily to preclude operation of said printing element by said mechanism during rapid adjustment of said slidewire.

2. A recorder com rising a slidewire adjustable to balance a measuring network, a printing element moved concurrently with rebalancing adjustment of said slidewire, actuating mechanism for periodically moving said printing element into engagement with the chart of said recorder, means for producing a voltage of magnitude dependent upon the speed of adjustment of said slidewire, connections for introducing said voltage into said network in avoidance of overshooting of the balance point, and electromechanical means responsive to said voltage tempor rily to preclude operation of said printing element by said actuating mechanism during adjustment of said slidewire.

3. A multi-range recorder comprising a rangeimpedance adjustable step-bystep and a smoothly variable impedance both included in a balanceable network for measurement of a variable throughout consecutive ranges of measurement, means responsive to positioning of the adjustable element of said smoothly variable impedance adjacent opposite limits to step said next higher or lower setting for balancing of said network within the limits or" said smoothly variable impedance, recording means coupled to said range-impedance for adjustment in step therewith to record in a marginal zone of the recorder chart a coarse indication of the measured variable, and recording means coupled to said adjustable element of the smoothly variable impedance for Vernier recording of the measured variable in a conti uous zone of the recorder chart, the recordings jointly precisely indicating the magnitude of the measured variable.

4. A. multi-range recorder as in claim 3, in in which the recording means respectively coupled to the range-i pedance and the smoothly variable impedance are distinct entities.

5. A multi-range recorder as in claim 3, in which a single recording means is at different times efiectively coupled to said range-impedance and to said smoothly variable impedance.

6. A multi-range recorder comprising a rangeimpedance adjustable step-by-step and a smoothly variable impedance both included in a balanceable network for measurement of a variable throughout consecutive ranges of measurement, a second range-impedance adjustable step-by-step and a second smoothly variable impedance both included in a second balanceable network, means responsive to positioning of the adjustable element of the first-named smoothly ance to its.

.impedance variable next higher or lower setting for balancing of said first-named network Within the limits of said first-named variable impedance and concurrently to step said second named range-impednext higher or lower setting, a de-- tector responsive at different times to the unbalances of said networks to effect rebalancing adjustments of said smoothly variable impedances; and recording means repositioned by the rebalancing adjustments to record a coarse indication of the magnitude of the measured variable while the detector is responsive to unbalance of said second network and to record a ver- .nier indication of the magnitude of the measured variable while the detector is responsive to unbalance of said first network.

'7. A multi-range recorder as in claim 4 in which .the recording means coupled to the smoothly variable impedance is a curve-tracing element, and in which the recording means coupied to the range-impedance is a print-wheel with peripherally spaced characters respectively corresponding with steps of the range impedance.

8. A multi-range recorder as in claim 4 in which each of the two recording means is a curve-tracing element engaging the chart in the corresponding one of said zones.

9. A multi-range recorder comprising a rangeadjustable step-by-step and a smoothly variable impedance both included in a balanceable network for measurement of a throughout consecutive ranges of measurement, recording means including a rangeprinting element coupled to said range-impedance, a mount for said range-printing element, means responsive to positioning of the adjustable element of said smoothly variable impedance adjacent opposite limits to step said range-impedance to its next higher or lower setting for balancing of said network within limits of said smoothly variable impedance and concurrently to step said range-printing element in either direction to a position corresponding with the new higher or lower measuring range, and actuating mechanism for intermittently moving said mount toward and from the chart of said recorder to effect printing thereon by said element of the range-impedance settings for which the network was balanced by adjustment of the smoothly variable impedance.

10. A multi-range recorder as in claim 9 in which the range-printing element is a printwheel angularly stepped in either direction to positions corresponding with the range-impedance settings, which additionally includes an inking wheel for engagement with such printwheel, and in which the mechanism for moving the mount of the print-wheel includes a differential for rotating the print-wheel between successive movements of the mount for transfer of ink from the inking roll and so insure legible printing on the chart when the same range setting is repeatedly printed for successive movements of the mount.

11. A multirange recorder as in claim 9 in which the mount of the range-printing element is stepped laterally in either direction transversely of the recorder chart to positions rein accordance with variations to be recorded,

spectively corresponding with the settings ofthe range-impedance.

12. A multi-range recorder as in claim 9 which additionally includes means for precluding movement of said printing-element mount when said adjustable element rapidly approaches either of said limits for stepping of said range-impedance to higher or lower setting including means producing an electrical effect of magnitude varying in accordance with the speed of said element, and electromechanical means responsive to said electrical effect to disable'said actuating mechanism during rapid movement of said adjustable element.

13. A multi-range recorder as in claim 12 which additionally includes connections for introducing said electrical effect into said balanceable network including said range-impedance and said smoothly variable impedance in opposition to the unbalance of the network.

14. A recorder comprising printing means in.- cluding at least one printing element positioned a pivotally-supported mount for said element intermittently rocked toward and from the chart of said recorder for effecting successive engagements therewith of said printing element, a link pivotally supported on said mount, a stationary member coacting with said link to swing it toward and back from said printing element upon rocking movement of said mount toward the chart, an arm pivotally connected to saidlink and having a cam surface, means for biasing said arm toward said mount, an inking element carried by said arm for movement respectively toward and back from a position between said printing element and the chart during movement of said mount away from and toward the chart, and a stop carried by said mount andcoacting with said cam surface to permit said biasing means to effect engagement between said inking and printing elements when said arm is in said position.

IRVING M. STEIN.

ALBERT J. WILLIAMS, Ja.

FRANK F. DERN, JR-

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 421,623 Shaw Feb. 18, 1890 721,187 Hepp Feb. 24, 1903 2,005,108 Pudelko June 18, 1935 2,113,069 Ross et al. Apr. 5, 1938 2,125,345 Hunt Aug. 1933 2,207,343 Fairchild July 1940 2,207,344 Fairchild July 9, 1940 2,209,717 Fairchild et al July 30,1940 2,288,679 Caldwell July 7, 1942 2,297,187 Johnson Sept. 29, 1942 2,400,828 Keinath May 21, .1 46 2,428,129 Smith Sept. 30, 1947 2, 08 Moseley Mar, 15, 1949 2,467,929 Colt "Apr. 1949 2,485,730 Giffen et a1. Oct. 25, 1949 2, 06,006 Wild May 2, 1950 FOREIGN PATENTS Number Country Date 120,169 Austria July ,9,- 1945 

